Directional flow sensor inhaler

ABSTRACT

An fluid sensor to activate and control various components of an inhalation device. The fluid sensor includes an acoustic element, such as a microphone, positioned within said inhalation device to detect fluid within the device and output signals representative of the frequency, direction and/or amplitude of the fluid. These signals control and activate an electrostatic plate and/or a high frequency vibrator.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to co-pending U.S. ProvisionalApplication entitled “Directional Flow Sensor Inhaler”, having Ser. No.60/547,324, Filed Feb. 24, 2004 which is entirely incorporated herein byreference.

TECHNICAL FIELD

The present invention relates generally to the field of inhalationdevices, and more specifically, to inhalation devices that utilizeacoustic control to facilitate breath activation of different systems ofthe inhalation device. Particular utility for the present invention isfound in the area of facilitating inhalation of powdered medications.

BACKGROUND OF THE INVENTION

Certain diseases of the respiratory tract are known to respond totreatment by the direct application of therapeutic agents. As theseagents are most readily available in dry powdered form, theirapplication is most conveniently accomplished by inhaling the powderedmaterial through the nose or mouth. Alternatively, the drug in this formmay be used for treatment of diseases other than those of therespiratory system. When the drug is deposited on the very large surfaceareas of the respiratory tract, it may be very rapidly absorbed into theblood stream; hence, this method of application may take the place ofadministration by injection, tablet, or other conventional means.

Several inhalation devices useful for dispensing this powder form ofmedicament are known in the prior art. For example, in U.S. Pat. Nos.3,507,277; 3,518,992; 3,635,219; 3,795,244; and 3,807,400, inhalationdevices are disclosed having means for piercing of a capsule containinga powdered medicament, which upon inhalation is drawn out of the piercedcapsule and into the user's mouth and thus, into the user's lungs andrespiratory system. Several of these patents disclose propeller means,which upon inhalation aid in dispensing the powder out of the capsule,so that it is not necessary to rely solely on the inhaled air to suctionpowder from the capsule. For example, in U.S. Pat. No. 2,517,482, issuedto Hall, a device is disclosed having a powder-containing capsule, whichis pierced by manual depression of a piercing pin by the user. U.S. Pat.No. 3,831,606 discloses an inhalation device having multiple piercingpins, propeller means, and a self-contained power source for operatingthe propeller means via external manual manipulation, so that uponinhalation the propeller means aids in dispensing the powder into thestream of inhaled air. See also U.S. Pat. No. 5,458,135.

The above description of the prior art is taken largely from U.S. Pat.No. 3,948,264 to Wilke et al, who disclose a device for facilitatinginhalation of a powdered medication. A capsule piercing structure isprovided, which upon rotation puts one or more holes in the capsule,which contains medication, so that upon vibration of the capsule by anelectro-mechanical vibrator, the powdered drug may be released from thecapsule. The electromechanical vibrator includes, at its innermost end,a vibrating plunger rod that is connected to a mechanical solenoidbuzzer for energizing the rod to vibrate. The buzzer is powered by ahigh-energy electric cell and is activated by an external button switch.Moreover, as noted above, in Wilke et al.'s disclosed device, vibrationof the powder is activated by depressing a push button. This can bedifficult and painful for some users (e.g., patients suffering fromextreme arthritis). Finally, in order to use Wilke et al.'s disclosedinhaler most efficaciously, the user must depress thevibration-actuating push button at precisely the same time that the userbegins inhalation. This can also be difficult for some users (e.g., veryyoung patients, patients suffering from neuromuscular disorders, etc.).

The prior art, such as described above, is dominated by inhaler devicesthat are activated by some mechanical means of activation, e.g., airflowsensors that include: flapper valves, turbine valves, swirl generators,vortex measurement devices, hot wire, direct pressure drop, ultra sonic,Doppler shift measurement, etc.

In our prior U.S. Pat. No. 6,152,130, issued Nov. 28, 2000, we providean inhalation device with a fluid sensor to activate and control variouscomponents of the device. The fluid sensor includes an acoustic element,such as a microphone, positioned within the inhalation device to detectfluid within the device and output signals representative of thefrequency and/or amplitude of the fluid. These signals control andactivate an electrostatic plate and/or a high frequency vibrator. Thisinhalation device provided improved utilization of mediation by ensuringthat the full (proper) dosage of the medicament is released when thepatient breathes. However, this acoustic sensor flow does not have theability to detect the direction of the flow of air. If the sensordetects a flow of air while user is exhaling, the medicament could bereleased at the wrong time and the patient would not receive the fulldose.

Thus, a heretofore unaddressed need exists in the industry to addressthe aforementioned deficiencies and inadequacies.

SUMMARY OF THE INVENTION

The present invention provides an improvement over the prior artinhalation devices such as our aforementioned U.S. Pat. No. 6,152,130.The present invention provides a directional acoustic flow sensor tooperate the inhaler. The direction acoustic flow sensor detects thedetection of the airflow into the inhaler and permits the activation ofthe inhaler when the user inhales and not when the user exhales. Apreferred embodiment includes an acoustic controller, wherein theacoustic controller includes an acoustic element to sense air flowaround the element and for producing signals representative of afrequency, direction and amplitude of the airflow, the signals beingused to control (e.g., activate, deactivate, apply incremental voltage,etc.) certain components of the inhalation device. This feature helpsmake the inhaler more user friendly, minimizes training necessary to usethe device and improves usability for children.

Preferably, the acoustic element is a microphone element or pressuretransducer positioned within the air passage of an inhalation device,(e.g., a dry powder inhaler) that produces signals in response to theinhalation air flow. These signals are used to control certaincomponents of the inhaler, e.g., a high frequency vibrator, anelectrostatic plate, timer, counter, etc. Also preferably, these signalsare used to activate/control certain components of the inhalation deviceto maximize the inhalation effectiveness to obtain maximum patientbenefit from the medicament.

Thus, the present invention provides a fully automated inhalationdevice, which is activated on inhalation only, that permits optimalutilization of the particular medication. For example, acoustic signalscan be used to trigger the high frequency vibrator only when the patienthas achieved optimum (e.g., maximum) inhalation effort, thereby ensuringthat the full (proper) dosage of medicament properly enters thepatient's respiratory system. Alternatively, these signals(breath-activated signals) can be used to progressively apply increasingpower to, or, sequentially activate/deactivate the various components ofthe inhalation device to achieve optimal inhalation dosage.

It will be appreciated by those skilled in the art that although thefollowing Detailed Description will proceed with reference being made topreferred embodiments and methods of use, the present invention is notintended to be limited to these preferred embodiments and methods ofuse. Rather, the present invention is of broad scope and is intended tobe limited as only set forth in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the invention can be better understood with reference tothe following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present invention. In the drawings,like reference numerals designate corresponding parts throughout theseveral views.

FIG. 1 is a cross-sectional view of a typical inhalation device and theacoustic controller of the present invention;

FIG. 2 is an expanded cross-sectional view of FIG. 1;

FIG. 3 is a functional block diagram of a preferred embodiment of thedirectional acoustic controller of the present invention;

FIG. 4 is a schematic diagram of the directional acoustic circuit; and

FIG. 5 is a timing diagram for the directional acoustic circuit.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a cross-sectional view of an airflow passage12 of an inhalation device 2 is depicted. It should be noted at theoutset that the airflow passage 12 depicted in FIG. 1 is a generalizedairflow passage of a typical inhalation device, such as those discussedabove. However, the present invention is intended to be adapted to anyinhalation device, regardless of the particular geometry of the airflowpassage. At its most basic level, the present invention operates byproviding an air flow sensor 8 to detect air flow turbulence around thesensor 8 (i.e., inspiratory air flow rate of a user of the inhaler) andto control various components of the inhalation device 2, as a functionof the amplitude, direction and/or frequency of the detected airflowturbulence, as described below.

As shown in FIG. 1, air 10 (or any other fluid) enters the airflowpassageway 12, typically by the respiratory activity of a patientinhaling on the device 2. As air 10 flows through the passage 12, aportion thereof flows through the opening 6 in the passage 2 into acavity 4. Placed within the cavity 4 is an air flow-sensing device 8.Preferably, the airflow-sensing device 8 is an acoustic sensing element,e.g. a microphone. Also preferably, microphone 8 is adapted to producean appropriate noise signal 48 in response to the airflow detectedwithin the cavity 4. The amplitude, direction, and frequency of theairflow within the cavity 4 are a function of the airflow rate 10 withinthe air passage 12 of the device 2. Thus, output noise signals 48 fromthe microphone 8 will vary in both frequency and amplitude as a functionof air flow rate and direction within the cavity (which is a function offlow rate within the passage 12), and thus, can be used to controlvarious components of the inhaler 2 as a function of frequency and/oramplitude, as described below. The shape of the cavity 4 and the size ofthe opening 6 should be chosen in accordance the particular geometry ofthe air passage 12, the air flow rate 10 through the passage 12, and/orthe frequency response and/or sensitivity of the microphone 8; and allsuch variations are within the scope of the present invention.Preferably, as noted above, the shape of the cavity 4 and the size ofthe opening 6 are chosen to permit at least a portion of the air withinthe passage 2 to enter the cavity 4 with sufficient amplitude to inducea response from the microphone 8.

Referring now to FIG. 2, an expanded cross-sectional view of anembodiment of the air flow sensor (described with reference to FIG. 1,above) in a dry powder inhaler, such as disclosed in U.S. Pat. No.5,694,920. Depicted in FIG. 2 are the components of a typically drypowder inhaler 2. A mouthpiece 46 is provided for a user (i.e., patient)to inhale on the device 2. A high-frequency vibratory mechanism 28(e.g., piezoelectric element, ultrasonic acoustic transducer, or otherelectro/mechanical vibratory mechanism, etc.) is provided to vibrate acontainer 20 (e.g., blister or capsule) of dry powdered medicament 50 tosuspend particles of the medicament into the air passage 12. To furtheraid the suspension of particles, an electrostatic potential plate 26 maybe provided to draw particles of a certain charge (i.e., a chargeopposite to that of the electrostatic plate 26) into the air stream 10.In this embodiment, a portion 10′ of the air 10 drawn into the airpassage 12 is induced into the cavity 4, to be detected by themicrophone element 8. Upon detection of airflow, the microphone elementproduces a noise signals 48. The noise signals 48 are used to controleither the high-frequency vibrator 28 and/or the electrostatic plate 26,or other components of the inhaler, as described below.

FIG. 3 is a block diagram representation of the acoustic control systemof the present invention for a dry powder inhaler. As described above,the microphone element 8 produces noise signals 48 in response todetected airflow 10′. These signals are processed by an processingcircuit 30 to condition the signals 48 and to determine the direction ofthe airflow and amplitude, and/or frequency of the noise signals 48. Theprocessor circuit 30 produces two signals: BREATH signal 60 and INHALEsignal 62.

The BREATH signal 60 is a logic level signal that indicates the presenceof an airflow in the inhalation device. The INHALE signal 62 is latchedat the rising edge of the BREATH signal 60 as an indicator of thedirection of the airflow. The state of the INHALE signal at the risingedge of the BREATH signal is a reliable indicator of the direction ofthe airflow in the channel during breathing. These signals are used tocontrol the high-frequency vibrator and/or electrostatic plate. To thatend, BREATH signal 60 is input into a comparator circuit 40 and/or 32and compared with a reference threshold signal 52 and/or 54,respectively. Furthermore, when the comparator circuit 40 and/or 32first detects a rising edge on the BREATH signal 60, the INHALE signal62 is latched by the comparator circuit 40 and/or 32. The high frequencyvibrator threshold 42 produces a signal 52 which represents the minimumvoltage and/or frequency required to activate the high frequencyvibrator controller 44 (which, in turn, activates the high frequencyvibrator 26). Comparator 40 compares signal 52 with BREATH signal 60 andif the signals have equal amplitude and/or frequency (within somepredetermined error margin) and the latched INHALE signal 62 is true,the comparator 40 activates the high frequency vibrator controller 44,which activates and directly controls the high frequency vibrator 26, asshown in FIG. 5. That is, if the BREATH signal 60 is above a referencethreshold, sufficient airflow exists in the air passage 12 to signifybreathing. Thus, the combination of the latched INHALE signal 62 beingtrue and the BREATH signal 60 being above a reference threshold (i.e.true) indicates that the user is inhaling. Similarly, a electrostaticplate deflector controller 36 is activated by an equal match of BREATHsignal 60 and signal 54 by the comparator 32 and a INHALE signal 62which is true. Electrostatic plate detector threshold 34 produces signal54 which represents the minimum voltage and/or frequency required toactivate the electrostatic plate 26.

The high frequency vibrator controller 44 and/or electrostatic platecontroller 36 assumes inhalation to be continuing as long as the BREATHsignal 60 remains true, independent of the subsequent changes of theINHALE signal 62. Upon the BREATH signal 60 becoming false i.e. thesignal falling below the threshold voltage, the high frequency vibrator28 and/or the electrostatic plate deflector 26 are deactivated

FIG. 4 is a schematic diagram including the microphone and the processorcircuit. Power to the microphone 8 used in the inhalation device issupplied via resistor 70. In this circuit, the noise signal 48 createdby air flow across the microphone 8 is communicated from the microphonevia capacitor 72 and amplified by the amplification circuit 100. Theamplification circuit consists of op-amp 74 and its associatedcomponents. This amplification circuit 100 also provides low passfiltering to reduce the sensitivity to unwanted signals. Capacitor 76,diode 78, diode 80, capacitor 82 and resistor 84 comprise arectification circuit 102 that outputs a logic level signal, BREATH,that is indicative of the presence of inhalation. The comparator circuit104 comprises an op-amp 86, resistor 88, resistor 90, capacitor 92, andresistor 94. The comparator circuit 104 is a comparator that detects theinitial direction of the airflow within the channel and outputs a signalINHALE.

The comparator circuit works as follows: Signal 48 is applied, via a lowpass filter (70, 72 and the virtual ground of 74), to the comparator.When breathing commences, signal 48 will have an instantaneous voltageoffset, relative to the voltage when there is no breathing, due to thechange of the pressure in air flow passage 12. The comparator sensesthis voltage offset by comparing the instantaneous voltage of signal 48with respect to a long term or low pass filtered version of signal 48,i.e., the signal created at the intersection of resistor 88 andcapacitor 92. At the instant when breathing commences, the differencebetween these two signals represents the direction of the breathing,whether it is an inhalation or exhalation. This difference is sensed bycomparator 86 which generates the INHALE signal 62. Other schemes orcircuits that exploit the difference between the instantaneous offset ofthe acoustic sensor signal at the commencement of breathing are withinthe spirit and scope of the present invention.

It should be understood that noise signal 48 is indicative of theairflow rate and direction 10, described above. The present inventionpreferably is intended to be controllable as a function of frequencyand/or amplitude of noise signals 48, thus, processor circuit can beadapted to condition the noise signals 48 in terms of amplitude orfrequency are both.

Another feature of this invention is an improved means for handlingtidal delivery of the medicament. Some users need multiple breaths toinhale the prescribed dosage of medicament because of asthma, decreasedlung capacity, etc. In this situation, the inhaler will manage thedosage as follows: at such time as the velocity of the air flow of aninhalation decreases below a threshold (the inhalation signal becomesfalse), dosing pauses; upon the beginning of another inhalation (boththe INHALE signal and the BREATH signal become true) dosing continuesuntil either 1) the dosing is complete or 2) the air flow velocity fallsbelow the aforementioned threshold. This process continues until dosingis complete or the cumulative time spent inhaling exceeds apredetermined limit.

Inspiratory capacity processor 38 is provided to compute the peakinspiratory flow 10 (represented by signals 48) of the patient. Althoughnot shown in the drawings, this information can be used to adjust thethreshold signals of the high frequency vibrator threshold 42 and/orelectrostatic plate detector threshold 34. Of course, to accomplishthis, the high frequency vibrator threshold 42 and/or electrostaticplate detector threshold 34 must be programmable, as is known in theart. In this way, the microphone 8 can be programmed to trigger thevarious components of the inhaler to adjust for varying inspiration flowrates from patient-to-patient or individually. Thus, for example, theinspirator control scheme of the present invention can be self-adjustingto account for a patient's decrease in inspiratory flow rate caused by,for example, decreased lung capacity. Alternatively, the processor 38can be modified to sequentially turn on the various components hereindescribed (e.g., vibrator, electrostatic plate, etc.) at optimalinhalation times (e.g., peak inhalation effort). Thus, for example, theprocessor 38 can be modified to activate the vibrator at a time justprior to the user's peak inhalation effort, then to activate theelectrostatic plate subsequently, thereby inducing the medicament intothe airstream at a time that produces optimal respiratory absorption ofthe medicament. Moreover, processor 38 can be adapted with appropriatememory to track a patient's inspiratory flow rate, which can be used toadjust the powdered medicament 50 to achieve maximum medication benefit.

Thus, it is evident that there has been provided an inhalation devicewith acoustic control and method for operating same that fully satisfyboth the aims and objectives hereinbefore set forth. It will beappreciated that although specific embodiments and methods of use havebeen presented, many modifications, alternatives and equivalents arepossible. For example, processing circuit 30, threshold signalgenerators 34 and 42, comparators 42 and 32 and can be any known digital(e.g., microprocessor) or analog circuitry and/or associated software toaccomplish the functionality described herein. Although the variouscomponents described in FIG. 3 have been described in a modular fashion,each of these components can be discrete off-the-shelf or customcomponents, or can be included in a single, unified system.

Also, the thresholding circuits 42 and 34, the amplitude/frequencyprocessor 30 and the inspiratory capacitor processor 38 can be adaptedto permit user (patient) control and user-definable presets (i.e.,minimum flow rate for activation, etc).

In addition, comparators 40 and 32 can be adapted to permit generationof activation signals based differing signal strengths and/or frequency.Thus, for example, the high frequency vibrator can be adapted toactivate only when a signal frequency of 1 Khz is achieved, while theelectrostatic plate will only activate when a signal strength of 35 mV.is obtained.

Other modifications are also possible. For example, the microphone 8 canbe positioned directly on the inner wall of the airflow passage 12 ofthe device 2, instead of within the cavity 4. In addition, as shown inFIG. 1, a turbulence generator 14 can be provided to generator airturbulence within the air passage 12. This modification, for example,can be used in an inhalation device that would otherwise not permit aportion 10′ of the air 10 to enter the cavity 4. In addition, instead ofa microphone 8, the acoustic element can be any known fluid pressuretransducer (e.g., air pressure transducer) that will output appropriatesignals as a function of fluid pressure (amplitude) and/or frequency.Accordingly, the present invention can be appropriately modified tooperate in any fluid medium (other than air), to provide automaticacoustic control.

Still other modifications are possible. For example, although not shownin the drawings, the present invention can be provided with a timer thatis controlled by signals 60 and 62. The timer can be appropriatelymodified to control a schedule of when the device may be activated, toavoid, for example, an overdose. Thus, for example, the timer may bemodified to only permit activation of the components of the device atcertain times of the day. Moreover, the timer may be appropriatelymodified to permit downloading of data related to usage (e.g., time ofday used, dosage of medicament, inhalation effort, etc.). This data canbe particularly relevant for clinical trials where it is important totrack the recommended dosage and times of medication. Of course, theprevious description could be accomplished with a counter, or the like,that simply counts the amount of times that the device has been used.Furthermore, the counter may be used to track the cumulative time a userhas used the device during a particular dosing or over a fixed length oftime.

Although the present invention has been directed to an acoustic controlscheme for a dry powder inhaler 2, the present invention is not solimited. On the contrary, the present invention is intended to beadapted for any inhalation device that would require a control mechanism(such as described herein) based breath (inhalation) detection. Forexample, an anesthetic device could be modified with the breath sensorand controller as provided herein to monitor and control the amount ofanesthetic a patient receives. Additionally, the acoustic sensingelement can be used to measure peak inspiratory and/or expiratory flowof a particular patient, and record this information for downloading andanalysis.

Although the preceding detailed description has provided severalembodiments of controlling various components of an inhalation deviceusing acoustic signals representative of the amplitude, direction and/orfrequency of inhalation, these have been provided only as examples ofachieving an acoustic control scheme, and other alternatives arepossible without departing substantially from the spirit and principlesof the invention. All such modifications and variations are intended tobe included herein within the scope of this disclosure and the presentinvention and protected by the following claims.

1. An air inhalation device for delivering medicament to a user, saiddevice comprising: an acoustic controller, said acoustic controllerincluding an acoustic sensing element configured to detect air flowaround said acoustic sensing element and to produce signals thatidentify the direction and amplitude of said air flow; and a highfrequency vibrator configured for inducing said medicament into said airflow when said signals indicate inhalation by said user.
 2. Aninhalation device as claimed in claim 1, further comprising anelectrostatic plate positioned in said air flow for attracting selectedparticles of medicament thereto, said electrostatic plate beingconfigured to activate when said signals indicate inhalation by saiduser.
 3. An inhalation device as claimed in claim 1, wherein saidacoustic controller is adapted to stop the vibration of said highfrequency vibrator when said signal indicates inhalation has stopped. 4.An inhalation device as claimed in claim 3, wherein said high frequencyvibrator is adapted to turn off and on with amplitude of air flow.
 5. Aninhalation device as claimed in claim 1, wherein said signals controlactivation of a timer, and said timer tracks cumulative inhalation time.6. An inhalation device as claimed in claim 5, wherein said timer isadapted to provide feedback to said user when cumulative inhalation timeexceeds a predetermined level.
 7. An inhalation device as claimed inclaim 1, wherein acoustic sensing element comprises an acousticmicrophone element.
 8. An inhalation device as claimed in claim 1,wherein said acoustic sensing element comprises an air pressuretransducer.
 9. An inhalation device as claimed in claim 1, wherein saidmedicament comprises a dry powder medicament.
 10. An inhalation deviceas claimed in claim 1, wherein said medicament is delivered from acontainer.
 11. An inhalation device for delivering powdered medicamentto a user comprising: an air flow passage; an acoustic controllerincluding an acoustic sensing element positioned within said air flowpassage, said controller being configured to detect air flow around saidacoustic sensing element and to produce signals representative of afrequency, amplitude and direction of said air flow; and a highfrequency vibrator for inducing said powdered medicament into saidairflow, wherein said high frequency vibrator is adapted to be activatedwhen said signal indicates inhalation and to be deactivated when saidsignal indicates inhalation has ceased.
 12. An inhalation device asclaimed in claim 11, wherein said high frequency vibrator is turned onand off a plurality of times until a prescribed amount of powderedmedicament is delivered.
 13. An inhalation device as claimed in claim11, wherein said signals control activation of a timer, said timertracks cumulative inhalation time.
 14. An inhalation device as claimedin claim 11, wherein said medicament is delivered from a container. 15.An airflow directional inhalation sensor comprising: an acoustic sensingelement configured to create a signal when air flows around saidacoustic microphone element and a conversion circuit to convert saidsignal into information regard direction and amplitude of said airflow.16. A directional inhalation sensor device as claimed in claim 15,wherein said conversion circuit includes a comparator circuit fordetecting an initial direction of said airflow.
 17. A directionalinhalation sensor device as claimed in claim 15, wherein said conversioncircuit includes a rectification circuit for detecting a velocity ofsaid air flow.